1. Technical Field
The present invention relates to wireless communications and, more particularly, to cellular wireless communication systems and a method of call setup therefor.
2. Related Art
Communication systems are known to support wireless and wire lined communications between wireless and/or wire lined communication devices. Such communication systems range from national and/or international cellular telephone systems to the Internet to point-to-point in-home wireless networks. Each type of communication system is constructed, and hence operates, in accordance with one or more communication standards. For instance, wireless communication systems may operate in accordance with one or more standards, including, but not limited to, IEEE 802.11, Bluetooth, advanced mobile phone services (AMPS), digital AMPS, global system for mobile communications (GSM), code division multiple access (CDMA), local multi-point distribution systems (LMDS), multi-channel-multi-point distribution systems (MMDS), and/or variations thereof.
Depending on the type of wireless communication system, a wireless communication device, such as a cellular telephone, two-way radio, personal digital assistant (PDA), personal computer (PC), laptop computer, home entertainment equipment, etc., communicates directly or indirectly with other wireless communication devices. For direct communications (also known as point-to-point communications), the participating wireless communication devices tune their receivers and transmitters to the same channel or channels (e.g., one of a plurality of radio frequency (RF) carriers of the wireless communication system) and communicate over that channel(s). For indirect wireless communications, each wireless communication device communicates directly with an associated base station (e.g., for cellular services) and/or an associated access point (e.g., for an in-home or in-building wireless network) via an assigned channel. To complete a communication connection between the wireless communication devices, the associated base stations and/or associated access points communicate with each other directly, via a system controller, via a public switch telephone network (PSTN), via the Internet, and/or via some other wide area network.
Each wireless communication device includes a built-in radio transceiver (i.e., receiver and transmitter) or is coupled to an associated radio transceiver (e.g., a station for in-home and/or in-building wireless communication networks, RF modem, etc.). As is known, the transmitter includes a data modulation stage, one or more intermediate frequency stages, and a power amplifier stage. The data modulation stage converts raw data into baseband signals in accordance with the particular wireless communication standard. The one or more intermediate frequency stages mix the baseband signals with one or more local oscillations to produce RF signals. The power amplifier stage amplifies the RF signals prior to transmission via an antenna.
Local Area Networks (wired LANS), e.g., Ethernets, support communications between networked computers and other devices within a serviced area. These wired LANs often link serviced devices to Wide Area Networks and the Internet. Each of these networks is generally considered a “wired” network, even though some of these networks, e.g., the PSTN, may include some transmission paths that are serviced by wireless links.
Wireless networks have come into existence more recently. Examples include cellular telephone networks, wireless LANs (WLANs), and satellite communication networks. Common forms of WLANs, such as IEEE 802.11(a) networks, IEEE 802.11(b) networks, and IEEE 802.11(g) networks, are referred to jointly as “IEEE 802.11 networks.” In a typical IEEE 802.11 network, a wired backbone couples to a plurality of wireless Access Points (APs), each of which supports wireless communications with computers and other wireless terminals that include compatible wireless interfaces within a serviced area. The wired backbone couples the APs of the IEEE 802.11 network to other networks, both wired and wireless, and allows serviced wireless terminals to communicate with devices external to the IEEE 802.11 network. Devices that operate consistently with an IEEE 802.11 protocol may also support ad-hoc networking in which wireless terminals communicate directly to one another without the presence of an AP.
WLANs now also support voice communications via wireless voice terminals. In supporting the wireless voice terminals, the WLAN works in cooperation with a Private Branch Exchange (PBX) to interface the WLAN with the PSTN. A serviced call is routed between the PSTN and a serviced wireless voice terminal via the PBX and the WLAN. In addition to WLANs, personal area networks (PANs) are gaining in popularity. Initially conceived to reduce cabling between devices, PAN technologies, and more specifically, Bluetooth based PANs or piconets, are adding yet another wireless layer to existing networks. For example, Bluetooth radios may be embedded in wireless headsets, printers, wireless keyboards, etc., to communicatively couple a peripheral device to a network component. For example, Bluetooth may be used to wirelessly couple a wireless headset to a handset that may be used in either a cellular network or merely in a PSTN based cordless phone. One problem not addressed in the prior art, however, relates to handoff of a wireless handset between cellular networks and especially the handoff of a wireless headset that is communicatively coupled to the wireless handset engaged in a cellular call to a specified landline docking station base unit that is operable to conduct telephone calls over the PSTN, and more particularly, a system and method for such handoff when a mobile station actively engaged in a call is docked in a docking station.